#include<bits/stdc++.h>
using namespace std;
#define int long long
signed main() {
	int a, b, n;
	cin >> a >> b >> n;
	int weeks = n / (a * 5 + b * 2);
	n %= (a * 5 + b * 2);

	int ans = 0;
	for (int i = 1; n > 0 && i <= 5; i++) {
		n -= a;
		ans++;
	}
	for (int i = 6; n > 0 && i <= 7; i++) {
		n -= b;
		ans++;
	}
	cout << ans + weeks * 7;
	return 0;
}
